Metallocene catalyst for the (CO)polymerization of .alpha.-olefins

Abstract

A catalyst active in the (co)polymerization of .alpha.-olefins is obtained by putting the following components in contact with each other:(i) a "bridged" bis-metallocene derivative of a metal M selected from titanium, zirconium or hafnium, wherein the divalent "bridge" has a rigid structure linked to two .eta..sup.5 -cyclopentadienyl ring with two methylene groups having a distance from each other of less than 3.5 .ANG.;(ii) a co-catalyst consisting of an organic derivative of a metal M' selected from boron, aluminium, gallium and tin.Such a catalyst allows high polymerization rates to be reached and is particularly suitable for high temperature polymerization process and co-polymerization of ethylene with other .alpha.-olefins.

Claims

1. A catalyst for the (co)polymerization of ethylene and/or.alpha.-olefins comprising the following two components put in contact with each other:

(i) a metallocene complex having the following general formula (I): ##STR14## wherein: M represents a metal selected from the group consisting of titanium, zirconium and hafnium,

A' and A" each independently represent an organic group containing a.eta..sup.5 -cyclopentadienyl anion co-ordinated to the metal M,

R' and R" each independently represent an anionic group linked to the metal M;

B represents a divalent organic group comprising an unsaturated group linked to two --CH.sub.2 --methylene groups so that they form with this unsaturated group a rigid molecular structure, and the distance between the two --CH.sub.2 methylene groups in the space is less than 3.5.ANG.;

(ii) a co-catalyst consisting of an organic compound of a metal M' selected from the group consisting of boron, aluminum, gallium and tin;

with the proviso that, when the groups A' and A" are both.eta..sup.5 -indenyl (C.sub.9 H.sub.7), the divalent organic group B is different from ortho-phenylene.

2. Catalyst according to claim 1, wherein at least one of, A' and A" is.eta..sup.5 -indenyl substituted with from 1 to 7 methyl groups on the ring.

3. Catalyst according to claim 1 or 2, wherein at least one of, A' and A" is.eta..sup.5 -indenyl substituted with from 1 to 4 methyl groups on the 6 atom ring.

4. Catalyst according to claim 1, wherein said divalent organic group B consists of condensed aromatic groups in which the atoms linked to the two methylene groups of formula (I) are in "peri" position on two adjacent aromatic rings.

5. Catalyst according to claim 1, wherein said divalent organic group B consists of an olefinically unsaturated group characterized by the presence of a --C.dbd.C-- group or a --C.dbd.N-- group.

6. Catalyst according to claim 1, wherein component (ii) is an aluminoxane.

7. Catalyst according to claim 1, wherein component (ii) is an ionizing compound capable of transforming the metallocene complex of formula (I) into a cationic form active in polymerization and becoming a non-coordinating inert anion.

8. Catalyst according to claim 7, wherein the molar ratio between the ionizing compound and the complex of formula (I) is within the range of 0.3 and 10.

9. Catalyst according to either claim 7, further comprising, besides components (i) and (ii), an aluminum trialkyl or alkyl-halogenide, having from 1 to 8 carbon atoms in each alkyl.

10. Catalyst according to claim 7, wherein said aluminum trialkyl or alkyl-halogenide is in such a quantity that the molar ratio between Al and the metal M in the complex of formula (I) is comprised within the range from 10 to 1000.

11. The catalyst according to claim 1, wherein R' and R" each independently represent a group selected from the group consisting of hydride, halide, C.sub.1 -C.sub.20 alkyl, C.sub.3 -C.sub.20 alkylsilyl, C.sub.5 -C.sub.20 cycloalkyl, C.sub.6 -C.sub.20 aryl, C.sub.1 -C.sub.20 alkoxyl, C.sub.1 -C.sub.20 thioalkoxyl, C.sub.2 -C.sub.20 dialkylamide and C.sub.4 -C.sub.20 alkylsilylamide.

12. The catalyst according to claim 2, wherein both A' and A" are.eta..sup.5 -indenyl substituted with from 1 to 7 methyl groups on the ring.

13. The catalyst according to claim 12, wherein both A' and A" are.eta..sup.5 -indenyl substituted with from 1 to 4 methyl groups on the 6 atom ring.

14. The catalyst according to claim 8, wherein the range is from 0.5 to 5.

15. The catalyst according to claim 8, further comprising, besides components (i) and (ii), an aluminum trialkyl or alkyl-halogenide, having from 1 to 8 carbon atoms in each alkyl.

16. The catalyst according to claim 14, further comprising, besides components (i) and (ii), an aluminum trialkyl or alkyl-halogenide, having from 1 to 8 carbon atoms in each alkyl.

17. The catalyst according to claim 10, wherein the range is from 100 to 500.

18. A process for the preparation of a co-polymer of ethylene and at least one.alpha.-olefin having at least 3carbon atoms, comprising co-polymerizing ethylene and said.alpha.-olefin in suspension, solution or gas-phase, at a temperature from 0.degree. to 250.degree. C., and at a pressure of from 1 to 1200 atms in the presence of a catalyst including the following two components put in contact with each other:

(i) a metallocene complex having the following general formula (I): ##STR15## wherein: M represents a metal selected from the group consisting of titanium, zirconium and hafnium,

A' and A" each independently represent an organic group containing a.eta..sup.5 -cyclopentadienyl anion co-ordinated to the metal M,

R' and R" each independently represent an anionic group linked to the metal M;

B represents a divalent organic group comprising an unsaturated group linked to two --CH.sub.2 -- methylene groups so that they form with this unsaturated group a rigid molecular structure, and the distance between the two --CH.sub.2 methylene groups in the space is less than 3.5.ANG.;

(ii) a co-catalyst consisting of an organic compound of a metal M' selected from the group consisting of boron, aluminum, gallium and tin.

19. A process according to claim 18, wherein said component (ii) is a polymeric aluminoxane, and the ratio between M in the compound of formula (I) and Al in the aluminoxane, ranges from 100 to 5000.

20. A process according to claim 18 or 19, wherein ethylene is co-polymerized with at least one.alpha.-olefin having from 3 to 8 carbon atoms, with a molar ratio of ethylene to said at least one.alpha.-olefin comprised from 0.05 to 10.

21. A process for the (co)polymerization of.alpha.-olefins, comprising polymerizing an.alpha.-olefin, or co-polymerizing a mixture of.alpha.-olefins, in suspension, solution or gas-phase, at a temperature above 100.degree. C., and at a pressure of from 1 to 1200 atms, in the presence of a catalyst according to the definition given in the preceding claim 12.

22. Process according to claim 21, wherein said group B in the complex compound of formula (I) is an aromatic group.

23. A process for the (co)polymerization of.alpha.-olefins, in suspension, at low, medium or high pressure and at temperatures of between 50.degree. and 240.degree. C., or in solution in an inert diluent operating at pressures of between 10 and 150 bars and temperatures of between 120.degree. and 230.degree. C., or in gas-phase, with temperatures within the range of 60.degree. to 160.degree. C., at pressures of between 5 and 50 bars, wherein an.alpha.-olefin or a mixture of.alpha.-olefins is made to polymerize in the presence of a catalyst according to anyone of claims 1 to 10 or claims 18 to 24.

24. The process of claim 18, wherein the.alpha.-olefin has 3 to 12 carbon atoms.

25. The process of claim 18, wherein the pressure is from 50 to 300 atms.

26. The process of claim 24, wherein the pressure is from 50 to 300 atms.

27. The process of claim 21, wherein the temperature is from 150.degree. to 240.degree. C.

28. The process of claim 21, wherein the pressure is from 500 to 1200 atms.

29. The process of claim 27, wherein the pressure is from 500 to 1200 atms.